MIMIC: An Adaptive Mixed Initiative Spoken Dialogue System for Information Queries

MIMIC: An Adaptive Mixed Initiative Spoken Dialogue System for Information Queries Jennifer Chu-Carroll Lucent Technologies Bell Laboratories 600 Mountain Avenue Murray Hill, NJ 07974, U.S.A. jencc @research.bell-labs.corn Abstract This paper describes MIMIC, an adaptive mixed initia- tive spoken dialogue system that provides movie show- time information. MIMIC improves upon previous dialogue systems in two respects. First, it employs initiative-oriented strategy adaptation to automatically adapt response generation strategies based on the cumu- lative effect of information dynamically extracted from user utterances during the dialogue. Second, MIMIC's dialogue management architecture decouples its initia- tive module from the goal and response strategy selec- tion processes, providing a general framework for devel- oping spoken dialogue systems with different adaptation behavior. 1 Introduction In recent years, speech and natural language technolo- gies have matured enough to enable the development of spoken dialogue systems in limited domains. Most ex- isting systems employ dialogue strategies pre-specified during the design phase of the dialogue manager with- out taking into account characteristics of actual dialogue interactions. More specifically, mixed initiative systems typically employ rules that specify conditions (generally based on local dialogue context) under which initiative may shift from one agent to the other. Previous research, on the other hand, has shown that changes in initiative strategies in human-human dialogues can be dynamically modeled in terms of characteristics of the user and of the on-going dialogue (Chu-Carroll and Brown, 1998) and that adaptability of initiative strategies in dialogue systems leads to better system performance (Litman and Pan, 1999). However, no previous dialogue system takes into account these dialogue characteristics or allows for initiative-oriented adaptation of dialogue strategies. In this paper, we describe MIMIC, a voice-enabled telephone-based dialogue system that provides movie showtime information, emphasizing its dialogue man- agement aspects. MIMIC improves upon previous sys- tems along two dimensions. First, MIMIC automat- ically adapts dialogue strategies based on participant roles, characteristics of the current utterance, and dia- logue history. This automatic adaptation allows appro- priate dialogue strategies to be employed based on both local dialogue context and dialogue history, and has been shown to result in significantly better performance than non-adaptive systems. Second, MIMIC employs an ini- tiative module that is decoupled from the goal selection process in the dialogue manager, while allowing the out- come of both components to jointly determine the strate- gies chosen for response generation. As a result, MIMIC can exhibit drastically different dialogue behavior with very minor adjustments to parameters in the initiative module, allowing for rapid development and comparison of experimental prototypes and resulting in general and portable dialogue systems. 2 Adaptive Mixed Initiative Dialogue Management 2.1 Motivation In naturally occurring human-human dialogues, speakers often adopt different dialogue strategies based on hearer characteristics, dialogue history, etc. For instance, the speaker may provide more guidance if the hearer is hav- ing difficulty making progress toward task completion, while taking a more passive approach when the hearer is an expert in the domain. Our main goal is to enable a spoken dialogue system to simulate such …

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